This invention relates to the cleaning of gloved or ungloved hands, and to the measurement of the state of cleanliness of the hands.
Workers in a wide range of fields must be certain that their hands are clean. In some cases, the workers wear gloves and in other cases they do not. For example, contaminants on the gloved hands of clean-room workers who work with microelectronic devices may have adverse consequences on product yields. Contaminants on the gloved or ungloved hands of medical and dental workers may transmit infections between patients or may contaminate apparatus. Contaminants on the gloved or ungloved hands of food-service workers may transmit diseases to customers.
The usual approach to hand cleaning in medical, dental, and food-service areas is a thorough washing in water with soap or a comparable disinfectant, and thorough drying. Where gloves are used, the gloves are changed. Such procedures are often mandated. However, studies have shown that in many cases medical, dental, and food-service workers do not follow the rules and do not avail themselves of the opportunity to wash their hands or change gloves, because it is inconvenient and time consuming to interrupt a task to wash and dry the hands or to change gloves. In the microelectronics fabrication field, workers are required to change gloves on a regular schedule, which is expensive in both glove costs and labor down-time.
The practice of wearing gloves has become increasingly widespread in these and other situations, to protect the workers, to protect the material being handled, and to protect third parties. The gloves, which are typically latex or a synthetic material, are cleaned and packaged by glove manufacturers or laundries, but may become contaminated with particles during shipping and storage. Elastomeric gloves are subject to surface hardening and microcracking. The microcracking allows particulate matter to be created and/or trapped at the microcracks. The particulate matter may later detach from the microcracks and surfaces of the gloves. The gloves may also become contaminated with biological organisms during use.
Thus, the failure to completely clean gloved or ungloved hands, and the costs associated with both cleaning the hands and failing to clean the hands, leads to problems in a wide range of fields. There is a need to improve the convenience and reduce the costs associated with the necessary cleaning of gloved or ungloved hands in clean room, medical, laboratory, food-service, and other environments. The present invention fulfills this need, and further provides related advantages.
The present invention provides an apparatus and method for cleaning gloved and ungloved hands to reduce the particulate content and surface chemical and biological contaminants to acceptable levels, and for measuring the particulate and/or contaminant content found on the surface of the gloved or ungloved hand. The apparatus may be readily used in clean room, medical, laboratory, food service, and other environments. It is a free-standing, self-contained unit except for a power connection, and does not require plumbing or drain connections. (The apparatus may be battery powered, and in that case does not even require an external power connection.) After cleaning of the gloved or ungloved hands, which usually requires less than 30 seconds, the gloved or ungloved hand is dry, so that the worker may immediately return to the activity which requires the cleaned hands. In applications involving gloved hands, the approach of the invention reduces the need to change gloves on a regular basis or, alternatively stated, increases the time between required changing of the gloves. The apparatus may also be used to monitor the number of times each person cleans the hands or changes gloves, and to correlate this information with manufacturing yields, health, or other parameters of interest.
In accordance with the invention, an apparatus has a hand-cleaning volume sized to receive a human hand therein. The apparatus comprises a mechanical-cleaning device including a pressurized gas source positioned to direct a flow of pressurized gas into the hand-cleaning volume, a source of pressurized gas in communication with an inlet of the pressurized gas source, and, optionally, a gas-source vent communicating with the hand-cleaning volume. The pressurized gas is an activated gas either in the form of an ionized gas or a plasma gas, but most preferably balanced ionized air. The flow of activated gas dislodges particles from the surface of the gloved or ungloved hand, and the activated gas aids in repelling the dislodged particles from the surface of the hand so that they do not redeposit thereon. The pressurized gas source may be a gas knife, such as an air knife in the form of a moving sheet of gas that sweeps over the surface of the hand, or a properly positioned set of nozzles that produce a turbulent atmosphere. The pressurized gas flow is preferably pulsed to increase the particle dislodging effects. The mechanical-cleaning device may include a particle counter in the gas-source vent to count particles dislodged from the gloved or ungloved hand. The particle count is interpreted as an indication of the cleanliness of the hands in respect to particles. The pressurized-gas source may also be operated to dry the gloved or ungloved hands after subsequent treatments.
The apparatus also includes a chemical-cleaning device. The chemical-cleaning device removes chemical and/or biological contaminants that may have adhered to the surface of the gloved or ungloved hand during prior use, but whose surface concentration must be reduced. The chemical-cleaning device includes a nebulizer operable to emit a cleaning mist into the hand-cleaning volume, a source of a cleaning solution in communication with an inlet of the nebulizer, and, preferably, a nebulizer vent disposed oppositely from the nebulizer across the hand-cleaning volume. The cleaning mist is in an activated state, such as a plasma gas or an ionized gas. Preferably, the cleaning mist is produced by passing a vapor of the cleaning solution through a plasma, to produce a dissociated, activated state in the cleaning mist. The activated cleaning mist thereafter passes across the hands received in the hand-cleaning volume.
The cleaning mist reacts with the chemical contaminants on the surface of the hand, mobilizes these contaminants, and causes them to vaporize and entrain in the flow of cleaning mist for removal from the system. The cleaning solution may be selected according to the type of contaminants that are expected in each application. In a typical case, however, organic contaminants are removed using an aqueous cleaning mixture of dissociated hydrogen peroxide, optionally an acid such as citric acid or lactic acid, and n-propyl alcohol. There may be, and preferably are, two or more cleaning solutions that are used sequentially to remove specific chemical contaminants. A skin conditioner may also be introduced in those cases where the hands are ungloved.
Biological agents may be removed by the cleaning mist, and/or a separate biological cleaning device such as an ultraviolet light source may be provided.
The apparatus further includes a controller operable to activate the mechanical-cleaning device and to activate the chemical-cleaning device and/or biological cleaning device during different time periods. In a typical situation, the mechanical-cleaning device is first operated for a period of time, typically 10 seconds or less, to dislodge particles. The chemical-cleaning device is then activated for a period of time, typically 10 seconds or less, to solubilize and remove chemical contaminants. The mechanical-cleaning device is then activated, to remove the condensed cleaning mist and any chemical contaminants dissolved in the condensed cleaning mist, by blowing them off the hand surface, and to dry the surface of the gloved or ungloved hand. If a second cleaning solution is to be used, the chemical-cleaning device is operated again using a second leaning solution, and the mechanical-cleaning device is thereafter operated to blow away any liquid on the surface, and to dry the surface. At the end of the cycle, the gloved or ungloved hand has been cleaned of particulate and chemical contaminants, and is dry and immediately ready for return to the activity being performed.
The apparatus is preferably placed in a housing, which has an opening therethrough which permits a person to place a gloved or ungloved hand (or both hands) into the hand-cleaning volume. The apparatus preferably includes a negative-pressure source within the housing adjacent to the opening, so that gas within the housing is preferentially drawn into the negative-pressure source rather than escapes through the opening. The negative-pressure source may be either the gas-source vent or the nebulizer vent, or a separate vent.
The method of the invention involves directing a flow of pressurized activated gas over the hand, and thereafter flowing a mist of a cleaning solution over the hand. The method is preferably, but not necessarily, performed in the apparatus described above. As will be discussed subsequently, the approach is highly flexible according to different cleaning requirements. An illustrative number of the approaches will be discussed subsequently.